It is proposed to conduct a thorough study of the accurate, precise and sensitive determination of N-nitrosamines of varying structures singly and in mixtures usng differential pulse polarography and differential polarography. These studies will be conducted in pure aqueous solutions as well as in biological fluids, such as blood serum, urine, gastric juice and tissue homogenates. Concurrent with the analytical study will be the determination of nitrosamine concentrations in blood, urine, gastric juice and tissue homogenates as a function of dose administered and time of sacrifice. The levels of nitrosamine in blood and liver in relation to the protective effects of diethyldithiocarbamate and other protective agents will also be determined. This direct application of the electroanalytical methods will establish the usefulness of these relatively new techniques in studies of nitrosamine carcinogenesis.